1. Field of the Invention
The present invention relates to a dielectric ceramic composition, a multilayer ceramic capacitor including a dielectric layer comprising the dielectric ceramic composition, and particularly the present invention relates to the dielectric ceramic composition having good IR characteristic and a high temperature accelerated lifetime.
2. Description of the Related Art
Recently, as the electronic circuit has become highly densified, the electronic component is demanded to be more compact, and the multilayer ceramic capacitor has rapidly become more compact with larger capacity, further the purpose of use has become wider, thus various characteristics are in demand.
For example, the mid-high voltage capacitor which is used at a high rated voltage (for example 100 V or higher) is suitably used for ECM (engine electric computer module), a fuel injection device, an electric controlled throttle, an inverter, a convertor, HID headlamp unit, a battery control unit for a hybrid engine, a digital steel camera or so.
In case of using it at a high rated voltage as mentioned in the above, it is used under high electric field intensity, but if the electric field intensity becomes higher, the specific permittivity and the insulation resistance or so decreases, hence as a result, the effective capacity or the reliability under the used environment may decrease.
For example, the patent document 1 discloses the multilayer ceramic capacitor comprising a dielectric layer comprising the dielectric particle having a core-shell structure. This dielectric particle comprises a concentration gradient of a sub component at a shell part, and the maximum value of the sub component concentration is found near the particle boundary, and near the boundary between the shell part and the core part. The multilayer ceramic capacitor using this dielectric particle has good a capacity-temperature characteristic and lifetime characteristic.
However, the multilayer ceramic capacitor described in the patent document 1 exhibited insufficient characteristic under high electric field intensity such as when applying DC voltage or so, and thus further improvement of the characteristics were demanded.